1. Field of the Invention
The present invention relates to a passive loudspeaker multiplexer to which a plurality of loudspeakers may be connected in parallel. Particularly, a plurality of different loudspeaker systems may be connected in parallel to an amplifier using the passive loudspeaker multiplexer according to the present invention.
2. Description of the Related Art
It is known that the number of loudspeakers and the resulting impedance connected to an amplifier is crucial in terms of matching the amplifier to a multi loudspeaker system. Most amplifiers cannot operate safely with loads having an impedance lower than 4Ω. Only few amplifiers can operate with a load of 2Ω. This is a major limitation when a considerable amount of loudspeakers have to be connected to an amplifier. Amplifier systems having an output voltage of 100 V are designed to distribute power to multiple speakers from a single amplifier. For several years these 100 V systems have been the only way to match a plurality of loudspeakers to an amplifier.
Further, resistive based impedance matching is known. Such systems typically consist of a network of resistors that are switched to the required configuration through a dial or switches. This requires a manual setting of the correct configuration based on the number of connected speakers.
Also transformer based impedance matching is known. Such impedance matching typically consists of using a transformer to provide the impedance matching. Mostly over some range this may be achieved dynamically without requiring to manually select the correct settings. However, such transformer introduces a power loss due to inefficiencies and possible distortions.
As an alternative an active design may be used to achieve an impedance matching. Active circuits allow detecting the speakers connected to such device. The required impedance matching circuit is activated by a resistive impedance matching or transformer based impedance matching.
U.S. Pat. No. 8,150,074 discloses an example of a manual resistive impedance matching.
However, the prior art has significant disadvantages. For example, resistive based impedance matching requires selecting the number of connected speakers via a dial. When using speaker cabinets with mixed impedances a wrong selection of the required settings may frequently occur. Transformer based designs typically introduce a power loss and distortions. Active designs require an external power supply and tend to be overly complex presenting more opportunities for failure. Further, active designs are not cost efficient.
Accordingly, it is an aspect of the present invention to provide a loudspeaker multiplexer that overcomes the limitations of the prior art.